JP2000142497A - Crawler expansion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve maintenance property by modifying an expansion mechanism of a crawler and reduce cost by decreasing weight, in a construction machine provided with a crawler expansion device. SOLUTION: A lower frame 1 comprises a cylindrical body 2 used for holding an upper structure turnable, axle beams 3f, 3r that are fixed back and forth of the cylindrical body 2 and extended right and left, and crawler frames 4L, 4R mounted to respective both ends of the axle beams 3f, 3r slidably right and left. A retract cylinder 25 is mounted to the cylindrical body 2, and is a double-acting cylinder in which pistons and piston rods are provided right and left of a cylinder tube. Tips of right and left piston rods 26L, 26R are passed through the substantially central parts of the right and left crawler frames 4L, 4R, and are connected with brackets 19L, 19R fixed to the outside surfaces of the crawler frames 4L, 4R.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crawler extension device for a construction machine having a crawler.
The present invention relates to a crawler expansion / contraction device for changing a tread of a body of a construction machine during transportation and during work.

[0002]

2. Description of the Related Art Large construction machines equipped with crawlers, such as crawler cranes and crawler backhoes, have a wide body tread in order to enhance stability during work. When transporting the construction machine, it is necessary to reduce the tread of the body so that it can be loaded on a truck. For this reason, this type of construction machine is provided with a crawler extension device for changing the tread of the body.

FIGS. 8 to 10 show a conventional crawler extension device of a construction machine, and FIGS. 8 and 9 show a state in which a tread of the body is contracted. In FIG.
Is a lower frame, and the lower frame 1 includes a cylindrical body 2 on which the upper rotating body is rotatably mounted, and a cylindrical body 2
Axle beams 3f, 3r fixed before and after and extending in the left-right direction, and crawler frames 4L, 4R slidably mounted on both ends of the axle beams 3f, 3r in the left-right direction. .

[0004] Guide holes 5L, 5R and 6L, 6R penetrating from the inner side to the outer side are respectively opened at the front part and the rear part of the left and right crawler frames 4L, 4R, and the front guide holes 5L, 5R are provided. Both ends of the front axle beam 3f are inserted and supported, and both ends of the rear axle beam 3r are inserted and supported in the rear guide holes 6L and 6R. Extending arms 7L, 7R and 8L, 8R are pivotally attached to both ends of each axle beam 3f, 3r so as to be horizontally rotatable.

When the tread shown in FIG. 1 is contracted, the extension arms 7L, 7R and 8L, 8R are folded forward or backward, and lug plates 9L, 9R protruding from the outer surfaces of the axle beams 3f, 3r. And 10L, 10R, the distal ends of these extended arms 7L, 7R and 8L, 8R are pin-connected. Also, the left and right crawler frames 4L,
Stopper arms 11L, 11R and 12L, 12R are provided on the inner surface of 4R substantially parallel to the axle beams 3f, 3r.
And lugs 13L, 13R and 14L, 14R protruding from the front or rear surfaces of the axle beams 3f, 3r.
The left and right stopper arms 11L, 11R and 12L,
The base end of 12R is pin-connected.

Here, retract cylinders 15L and 15R are mounted on the cylindrical body 2, and the retract cylinders 15L and 15R are single-rod double-acting cylinders, respectively. is there. An opening 16 is provided below the cylindrical body 2. A bottom plate 17 is provided at the center of the opening 16, and the bottom plate 17 is provided.
A bracket 18 is erected on the right side to connect the head sides of the left and right retract cylinders 15L and 15R. In addition, the rod ends of the retract cylinders 15L and 15R are
The right and left crawler frames 4L and 4R pass through substantially the center portions thereof and are connected to brackets 19L and 19R fixed to outer surfaces of the crawler frames 4L and 4R.

[0007] When the vehicle is transported by being loaded on a truck, the vehicle is transported in a tread contracted state shown in FIG.
If the aircraft is to be in a working position after being transported to the destination, jack up the aircraft and extend the tread. When expanding the tread, for example, when expanding the right crawler frame 4R, first, release the pin connection between the right extending arms 7R, 8R and the front and rear lug plates 9R, 10R,
Stopper arms 11R, 12R and lug plates 13R, 14R
And release the pin connection, as shown by the two-dot chain line in FIG.
The extension arms 7R and 8R are turned by approximately 90 degrees to be parallel to the longitudinal directions of the axle beams 3f and 3r.

In this state, the right retract cylinder 1
When the 5R is driven to the extension side, the cylinder rod of the retract cylinder 15R is extended by using the bracket 18 erected on the cylindrical body 2 as a reaction force receiving member, and as shown in FIG. Move outward of. Then, after extending the retract cylinder 15R to the full stroke, the stopper arm 11R,
12R and the lug plates 13R and 14R are pin-connected, and the right crawler frame 4R is connected to the front and rear axle beams 3f and 3R.
fixed to r.

Although not shown, when expanding the left crawler frame 4L, the pin connection of the left extension arms 7L, 8L and the stopper arms 11L, 12L is released, and the left retract cylinder 15L is driven to the extension side. Then, the left crawler frame 4L moves to the outside of the body. In this way, the tread of the body is expanded to the working posture. On the other hand, when changing from the working posture to the carrying posture, the tread of the body is contracted by performing an operation reverse to that described above.

[0010]

In the conventional crawler telescopic device, a bracket is erected on the bottom of an opening of a cylindrical body as a reaction force receiving when the left and right retract cylinders are driven. Originally, this opening had to be wide open for maintenance of hydraulic equipment and hydraulic piping, etc., but in order to support the weight and reaction force of the left and right retract cylinders, a bottom plate was installed to increase the strength. I have.
Therefore, the opening of the cylindrical body becomes small, so that the maintainability is reduced, and the weight increases to cause a cost increase.

Therefore, in a construction machine equipped with a crawler expansion / contraction device, there is a technical problem to be solved in order to improve the maintainability by improving the expansion / contraction mechanism of the crawler and to reduce the weight by reducing the weight. The present invention aims to solve this problem.

[0012]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above-mentioned object, and is a lower frame of a construction machine. A cylindrical body, an axle beam fixed in front of and behind the cylindrical body and extending in the left-right direction, and a crawler frame slidably mounted on both ends of the axle beam in the left-right direction, In a crawler telescopic device in which a retract cylinder is mounted on the body and the left and right crawler frames are slid by the retracting operation of the retract cylinder, and the tread of the fuselage is formed to be able to expand and contract, the retract cylinder includes both right and left cylinder tubes. A retractable cylinder provided with a bracket on the inner surface of the cylindrical body. Receiving the reaction force upon the piston drive,
It is an object of the present invention to provide a crawler expansion / contraction device in which left and right piston rod tips of the retract cylinder are connected to left and right crawler frames, respectively.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. For convenience of explanation, the same reference numerals are given to the same components as those in the related art, and the description thereof will be omitted. 1 and 2 show the lower frame 1 of the construction machine in a state where the tread of the body is contracted, and a retract cylinder 25 is mounted on the cylindrical body 2. The retract cylinder 25 is a double-acting cylinder provided with a piston and a piston rod on both the left and right sides of a cylinder tube, and the distal ends of the left and right piston rods 26L, 26R pass through substantially the center of the left and right crawler frames 4L, 4R. The brackets 19 fixed to the outer surfaces of the crawler frames 4L and 4R.
L, 19R.

A bracket 27 is fixed substantially at the upper center of the retract cylinder 25, and an arm 29 is interposed between a bracket 28 projecting from the inner surface of the cylindrical body 2 and the bracket 27 of the retract cylinder 25. Dress up
The two brackets 27 and 28 are pin-connected. The bracket 28 supports the weight of the retract cylinder 25 and receives a reaction force when the piston is driven. Further, since the bracket 28 projects substantially horizontally from the inner surface of the cylindrical body 2, it is not necessary to extend a bottom plate on the opening 16 of the cylindrical body 2 as in the conventional type, and the opening 16 is widened. Can be opened.

FIG. 3 shows a hydraulic circuit of the retract cylinder 25. The retract cylinder 25 is provided with pistons 30L and 30R on both the left and right sides. One piston rod 26L projects to the left and the other piston rod 2
6R protrudes rightward. The retract cylinder 25 is provided with rod-side ports 31L, 31 provided on the left and right.
It has three ports, R and a head-side port 31C provided at the center, and each port is connected to a hydraulic pump 34 via direction control valves 32 and 33. As shown, when each of the directional control valves 32 and 33 is in the neutral position N, the hydraulic oil discharged from the hydraulic pump 34 returns to the tank 35 by bypassing the directional control valves 32 and 33 at the center.

When transporting the vehicle by loading it on a truck, the directional control valves 32 and 33 are set to the neutral position N to close the oil passages leading to the respective ports 31L, 31R and 31C. And as shown in FIG. 2, the tread of the body is conveyed in a contracted state.

Here, when the aircraft is brought into the working posture after being transported to the destination, the aircraft is jacked up to extend the tread. For example, when expanding the right crawler frame 4R, first, the pin connection between the right extending arms 7R, 8R and the front and rear lug plates 9R, 10R is released, and the stopper arms 11R, 12R and the lug plates 13R, 14R are disengaged. Is released, and the extending arms 7R, 8R are turned approximately 90 degrees to be parallel to the longitudinal directions of the axle beams 3f, 3r, as shown by the two-dot chain line in FIG.

In this state, as shown in FIG. 4, when one of the directional control valves 32 is switched to the extended position E, the hydraulic oil discharged from the hydraulic pump 34 is moved to the extended position E of the directional control valve 32. To the head side port 31C of the retract cylinder 25. At this time, since the left rod-side port 31L is closed at the neutral position N of the direction control valve 33, the left piston 30L does not move. On the other hand, the right rod-side port 31R communicates with the tank 35 through the extended position E of the direction control valve 32. Accordingly, the right piston 30R moves rightward as indicated by the two-dot chain line.

That is, the right piston rod 26R of the retract cylinder 25 is extended, and as shown in FIGS.
The right crawler frame 4R moves outward of the body. After extending the retract cylinder 25 to the full stroke, the stopper arms 11R, 12R
The right crawler frame 4R is fixed to the front and rear axle beams 3f, 3r by connecting the R and the lug plates 13R, 14R with pins.

Next, in order to widen the left crawler frame 4L, the pin connection of the left extension arms 7L, 8L and the stopper arms 11L, 12L is released, and as shown in FIG. Is switched to the neutral position N and the other directional control valve 33 is switched to the expanded position E, the hydraulic oil discharged from the hydraulic pump 34 passes through the expanded position E of the directional control valve 33 and the head side port of the retract cylinder 25 31C. At this time, since the right rod-side port 31R is closed at the neutral position N of the direction control valve 32, the right piston 30R does not move. On the other hand, the left rod side port 31 </ b> L communicates with the tank 35 through the extended position E of the direction control valve 33.

Accordingly, the left piston 30L moves to the left as shown by the two-dot chain line, the left piston rod 26L of the retract cylinder 25 extends, and the left crawler frame 4L moves outward of the body. Thus, both the left and right crawler frames 4L, 4R are widened, and the tread of the body is expanded to the working posture.

The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified ones.

[0023]

According to the present invention, a double-acting cylinder provided with a piston and a piston rod on both left and right sides of a cylinder tube is mounted on a cylindrical body of a lower frame of a construction machine, as described in detail in the above embodiment. Since a bracket is provided on the inner surface of the cylinder to receive the reaction force of the retract cylinder, there is no need to install a bottom plate at the opening of the cylinder to fix the reaction force receiver as in the conventional type. The opening can be opened widely. Therefore, maintenance of the hydraulic equipment and the hydraulic piping can be easily performed, and the weight can be reduced to contribute to cost reduction.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, and is a partially cutaway plan view of a lower frame in a state in which a tread of an airframe is contracted.

FIG. 2 is a partially cutaway longitudinal front view taken along the line AA of FIG. 1;

FIG. 3 is a hydraulic circuit diagram of a retract cylinder in a state where left and right piston rods are contracted.

FIG. 4 is a hydraulic circuit diagram of a retract cylinder in a state where a right piston rod is expanded.

FIG. 5 is a partially cutaway plan view of the lower frame with the right crawler frame expanded.

FIG. 6 is a partially cutaway longitudinal front view taken along the line BB of FIG. 5;

FIG. 7 is a hydraulic circuit diagram of the retract cylinder in a state where the left piston rod is expanded.

FIG. 8 is a partially cutaway plan view of the lower frame in a state where the tread of the body is contracted, showing the conventional crawler extension device.

FIG. 9 is a partially cutaway vertical sectional front view taken along line CC of FIG. 8;

FIG. 10 is a partially cutaway plan view of the lower frame with the right crawler frame expanded, showing the conventional crawler extension device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower frame 2 Cylindrical body 3f, 3r Axle beam 4L, 4R Crawler frame 25 Retract cylinder 26L, 26R Piston rod 27, 28 Bracket 29 Arm 30L, 30R Piston

Claims (1)

[Claims] 1. A lower frame of a construction machine, wherein the lower frame is provided with a cylindrical body on which an upper rotating body is pivotably mounted, and is fixed before and after the cylindrical body and extends in the left-right direction. Axle beam, and a crawler frame slidably mounted on both ends of the axle beam in a lateral direction, a retract cylinder is mounted on the cylindrical body,
In the crawler telescopic device in which the left and right crawler frames are slid by the retracting operation of the retract cylinder to expand and contract the tread of the machine body, the retract cylinder has a piston and a piston rod provided on both left and right sides of a cylinder tube. A double-acting cylinder, wherein a bracket is provided on the inner surface of the cylindrical body to receive a reaction force at the time of driving the piston of the retract cylinder, and the tip ends of the left and right piston rods of the retract cylinder are connected to the left and right crawler frames, respectively. Crawler telescopic device.